Removing liquid containing capillary layer from material being centrifuged



I E. RUEGG REMOVING LIQUID CONTAINING CAPILLARY LAYER Feb. 5, 1963 FROM MATERIAL BEING CENTRIFUGED 3 Sheets-Sheet 1 Filed Jan. 28, 1960 INVENTOR. Er n st R Lleg 9 BY a A torneys Feb. 5, 1963 E. R'u'EGG 3,076,552

REMOVING LIQUID CONTAINING CAPILLARY LAYER FROM MATERIAL BEING CENTRIFUGED ilk INVENTOR.

Ernst Riiegg Attorneys Feb. 5, 1963 RUEGG 3,076,552

REMOVING LIQUID CONTAINING CAPILLARY LAYER FROM MATERIAL BEING CENTRIFUGED Filed Jan. 28, 1960 3 Sheets-Sheet 3 zfi 4 E191 INVEN' TOR.

Ernst R'u'egq BY 9% MQSM Attorneys United States Patent 3076552 REMOVING LIQUID ,COIVTAINING CAPILLARY 52m FROM MATERIAL BEING CENTRI- Ernst Ruegg, Kusnacht, Switzerland, assignor to Escher Wyss Aktiengesellschaft, Zurich, Switzerland, a corporation of Switzerland Filed Jan. 28, 1960, Ser. No. 5,177 Claims priority, application Switzerland Mar. 2, 1959 3 Claims. (Cl. 210-376) This invention relates to a device by which separation of liquid from the material being centrifuged in the centrifugal drum of a centrifuge, more particularly a continuously operating push-type centrifuge, is improved.

In continuously operating push-type centrifuges, the material being centrifuged is gradually conveyed over the strainer surface of the centrifugal drum by means of a pusher member from the supply end toward the discharge end of the drum and then falls into a collector.

In the course of its progressive movement in the drum,

Patented Feb. 5, 1963 Ice the pusher member 4. The strainer device 7 is shown in FIG. 2 on a larger scale. It comprises a strainer cylinder 9 situated in the drum 3 and provided with holes 10 which open into spaces 11 with discharge openings 12 of the drum 3. The inner surface of the cylinder 9- is smooth.

. chambers 15 arranged so as to co-operate with the perfoliquid is continuously removed from the material, until at the discharge end of the drum, there is immediately on the strainer a capillary layer containing liquid which can no longer be removed by centrifuging, and above this layer is centrifugally dry solid material with uniformly distributed moisture.

The capillary layer entering the collector along with the centrifugally dry solid material and still containing liquid, promotes the formation'of drifts in the collector and impairs the degree of dryness, since its liquid content can substantially increase the mean moisture content of the solid material discharged into the collector.

It is the object of the invention to obviate the disadvantages described. In a continuously operating centrifuge which comprises at least one rotatable sieve drum having a supply end and a discharge end, means for feed ing material to be centrifuged to said supply end, and conveying means arranged within said sieve drum by which a layerof the material fed'to the supply end is conveyed toward said discharge end while being centrifuged, the sieve drumis provided for this purpose, according to the invention, with means for separately discharging a fraction of material immediately adjacent the drum. By these means it is possible to remove at least a part of the capillary layer formed in the material being centrifuged, so that a higher degree of dryness for the material discharged into the collector can be obtained.

constructional examples of the subject of the invention are represented in simplified form in the drawing, wherein: I

FIG. 1 shows an axial vertical section through a pushtype centrifuge.

FIG. 2 shows the discharge end of the sieve drum shown in FIG. 1, on a larger scale.

FIG. 3 shows an axial vertical part section through the sieve drums of a two-stage push-type centrifuge.

FIGS. 4 to 6 show part sections through sieve drums with an annular funnel at the drum end, and

FIG. 7 shows a device with re-centrifuging drum.

The continuously operating push-type centrifuge shown in FIG. 1 has a housing 1 with a collector 2, a rotatable sieve drum 3 having a supply end and a discharge end, a pusher member 4 arranged within the sieve drum 3 at the supply end thereof so as to be axially reciprocatable in relation to the drum 3, and an inlet hopper 5 for feeding material to be centrifuged arriving from an inlet pipe 6 to the supply end of the drum 3.

The drum 3 is provided with a strainer device 7, on which a layer 8 of material being centrifuged is advanced gradually in the axial direction from the supply end toward the discharge end of the drum 3 by means of rations 14 of the drum section. The material being centrigued is conveyed over the strainer cylinder 7 and travels over the perforations 14, which are so arranged or formed that they comprise all generatrices of the strainer cylinder. The capillary layer then passes into chambers 15 of the sluicing slider 16 (when the slider is in the position shown in FIG. 2).

If the slider 16 is moved fromthe position shown in FIG. 2 to the position shown in FIG. 1, the capillary layer portions fall from the chambers 15 through openings 17 of the centrifugal drum into a collector 18. In addition to the capillary layer the liquid film forming on the strainer cylinder 7 is also sluiced out by these measures.

In this way, only the centrifugally dry layer of the centrifuged material with uniformly distributed moisture, passes into the collector 2, which means that the performance of the centrifuge is increased and a substantial improvement is obtained in the quality of the solid material discharged.

The slider 16 is moved by means of rods 19. The latter are connected with the pusher member 4 as indicated in FIG. 1.

In the drums 20 and 21 of the two-stage push-type centrifuge shown in FIG. 3, a sluicing slider 22 of the drum 21 is connected by rods 23 to the adjacent drum 20 which acts as a pusher member for the material being centrifuged within the drum 21.

According to FIG. 4 the device for discharging the capillary layer comprises an annular funnel 25 fixed to the discharge end of the drum 24 filled with material being centrifuged, a layer 27 of the said material moving forward on the drum. The inlet opening 26 of said funnel is flush with the interior surface of the sieve drurn, so that the material travels over said opening.

The capillary layer of the layer 27 of the material being centrifuged, at the point of contact of the funnel charge, gives up its moisture to the latter. At the discharge opening 28 of the funnel 25, which is situated radially outward of the inlet opening 26, a capillary layer is then formed again. If the opening 28 is suitably dimensioned, this'latter layer discharges of its own accord into a collector 29, and a corresponding quantity of material enters through the opening 26.

In the case of the annular funnel 30 shown in FIG. 5, a sluicing slider 31 is provided for intermittent sluicing of the capillary layer. The mode of operation of the sluice 30, 31 corresponds to that of the sluice 13 according to FIGS. 1 and 2.

The device according to FIG. 6 also has an annular funnel, namely the funnel 33, arranged at the drum end 32. At its discharge end, the funnel 33 extends into an annular channel of U-shaped cross-section containing a solvent liquid flushing bath 34. The solvent liquid is fed to the bath via conduit 35. The capillary layer and possibly also other portions of the centrifuged material are dissolved by the solvent and are discharged through perforations 36 in a side wall of the bath channel into a collector 37.

The inlet opening of the funnel 33 may be covered entirely or partly by a strainer or strainer bars on which slides the layer of centrifuged material pushed over the opening.

If necessary, the strainer device may have over a large portion of the drum length or over the entire drum, sluicing devices for the capillary layer or its liquid.

In multi-stage centrifuges, all the stages can be constructed in the manner described. In most cases, however, it will suffice if the last drum of the centrifuge is equipped at its discharge end in the manner described. The capillary layer sluiced out of the drum may in certain circumstances be added to the layer of centrifuged material situated in another drum. The sluiced out capillary layer, however, may also be passed to a separate drum and be re-centrifuged in the latter.

In the constructional for-m according to FIG. 7, a further sieve drum 38, re-centrifuging the capillary layer, follows an annular funnel 39, arranged at the discharge end of a sieve drum. The funnel 39 forms the supply funnel for said re-centrifuging drum 38. The supply end of the latter encircles the funnel 39 in close proximity to the discharge opening thereof. The drum 38 is axially shiftable in relation to the funnel 39 and the sieve drum connected therewith in the same way as the sluicing slider 16 or 22 of the constructional forms shown in FIGS. 1 to 3. The funnel 39 is so shaped as to act as a pusher member for the material to be conveyed within the re-centrifuging drum 38.

The capillary layer arriving wet on the drum 38 will not at first be very capable of being pushed and will pile up. After a suitable quantity of liquid has been removed by centrifuging, however, it will form a layer which can be pushed. It is true that a capillary layer will again be formed in the latter, but it will hardly be of any significance quantitatively, compared with the total quantity of discharged centrifuged material.

A centrifugally dry layer 41 advancing over the inlet opening of the funnel 39 passes over an annular guide plate 42 into a collector 43, while the layer 40 issuing from the re'centrifuging drum 38 falls into a collector 44. Both layers (48, 41), however, may be led into a common collector.

What is claimed is:

1. In a continuously operating centrifuge including at least one rotatable sieve drum having a supply end and a discharge end, means for feeding material to be centrifuged to said supply end, and conveying means for conveying the material during centrifugation toward said discharge end, the improvement which comprises:

a. a sluicing device for separately discharging at least a portion of the material lying immediately adjacent the inner peripheral surface of the drum, said sluicing device comprising:

(1) an opening through the drum in the path of travel of the material moving toward said discharge end and dimensioned to allow passage of said material therethrough;

(2) a member connected with the drum and spaced radially from its outer periphery, the member being imperforate in the region of said opening and containing a passage spaced from said opening; and

(3) a sluicing slider carried by the drum and interposed between the drum and said member, the slider containing a chamber and being movable relatively to the drum between first and second positions in which, respectively, the chamber registers with the opening and the passage, the slider being so arranged that as it moves from the first to the second position the chamber is disconnected from said opening and then connected with said passage, and as it moves from the second to the first position the chamber is disconnected from said passage and then connected with said opening.

2. In a continuously operating push-type centrifuge including at least one rotatable sieve drum having a supply end and a discharge end, means for feeding material to be centrifuged to said supply end, and a longitudinally reciprocable pusher located in the drum and arranged to convey the material during centrifugation toward said discharge end, the improvement which comprises:

a. a plurality of circumferentially spaced openings extending through the drum near the discharge end thereof, the openings being dimensioned to allow passage of said material therethrough;

b. a sleeve connected with and spaced radially from the outer periphery of the drum, the sleeve being imperforate in the region of the openings but containing a circumferential series of through radial passages spaced longitudinally from said openings;

c. an annular sluicing slider interposed between the drum and the sleeve and containing a plurality of through chambers, the slider being reciprocable in the longitudinal direction of the drum between a first position in which the chambers register with said openings and a second position in which the chambers register with said through radial passages;

d. means carried by the slider for closing said openings as the slider moves from the first to the second position; and

a. means connecting the slider with the pusher so that the former is reciprocated by the latter.

3. The improvement defined in claim 2 in which the openings are so positioned that they cross all generatrices of the sieve drum.

References Cited in the file of this patent UNITED STATES PATENTS 2,686,595 Cox Aug. 17, 1954 2,755,934 Ruegg July 24, 1956 2,899,065 Irving Aug. 11, 1959 2,982,411 Fontein May 2, 1961. 2,991,887 Wirth et al July 11, 1961 FOREIGN PATENTS 201,513 Austria Jan. 10, 1959 506,534 Italy Dec. 23, 1954 720,919 Great Britain Dec. 29, 1954 

2. IN A CONTINUOUSLY OPERATING PUSH-TYPE CENTRIFUGE INCLUDING AT LEAST ONE ROTATABLE SIEVE DRUM HAVING A SUPPLY END AND A DISCHARGE END, MEANS FOR FEEDING MATERIAL TO BE CENTRIFUGED TO SAID SUPPLY END, AND A LONGITUDINALLY RECIPROCABLE PUSHER LOCATED IN THE DRUM AND ARRANGED TO CONVEY THE MATERIAL DURING CENTRIFUGATION TOWARD SAID DISCHARGE END, THE IMPROVEMENT WHICH COMPRISES: A. A PLURALITY OF CIRCUMFERENTIALLY SPACED OPENINGS EXTENDING THROUGH THE DRUM NEAR THE DISCHARGE END THEREOF, THE OPENINGS BEING DIMENSIONED TO ALLOW PASSAGE OF SAID MATERIAL THERETHROUGH; B. A SLEEVE CONNECTED WITH AND SPACED RADIALLY FROM THE OUTER PERIPHERY OF THE DRUM, THE SLEEVE BEING IMPERFORATE IN THE REGION OF THE OPENINGS BUT CONTAINING A CIRCUMFERENTIAL SERIES OF THROUGH RADIAL PASSAGES SPACED LONGITUDINALLY FROM SAID OPENINGS; C. AN ANNULAR SLUICING SLIDER INTERPOSED BETWEEN THE DRUM AND THE SLEEVE AND CONTAINING A PLURALITY OF THROUGH CHAMBERS, THE SLIDER BEING RECIPROCABLE IN THE LONGITUDINAL DIRECTION OF THE DRUM BETWEEN A FIRST POSITION IN WHICH THE CHAMBERS REGISTER WITH SAID OPENINGS AND A SECOND POSITION IN WHICH THE CHAMBERS REGISTER WITH SAID THROUGH RADIAL PASSAGES; D. MEANS CARRIED BY THE SLIDER FOR CLOSING SAID OPENINGS AS THE SLIDER MOVES FROM THE FIRST TO THE SECOND POSITION; AND E. MEANS CONNECTING THE SLIDER WITH THE PUSHER SO THAT THE FORMER IS RECIPROCATED BY THE LATTER. 